Regulators are devices that allow scuba divers to breathe air, or the like, while under water. The regulator uses valves to release air from high pressure tanks, typically through the action of an inhalation responsive diaphragm. Most often, a first stage regulator is attached to the tank. A second stage regulator is then connected to the first by a flexible hose and is supported by a mouthpiece retained in the mouth of the diver. This configuration requires minimal breathing effort since it locates the inhalation responsive elements closer to the center of pressure of the diver's lungs.
The regulator further includes a no-return exhaust valve mounted within the housing or incorporated into the inhalation diaphragm. Since exhalation occurs back through the regulator, the inhalation chamber is filled with expired air before the next inhalation cycle. U.S. Pat. No. 2,747,572, to Gagnan, locates the demand valve close to the respiratory port while placing the exhaust valve at a much greater distance, thus minimizing, though not entirely eliminating, the re-inhalation of expired air.
Due to its open nature, the second stage regulator can flood with corrosive salt water and abrasive sand and silt. U.S. Pat. No. 4,079,735, to Gaffney, shows a plug that fits into the mouthpiece to prevent the regulator from flooding when not in use, thus extending its serviceable life. However, the regulator may still flood when the plug is removed before use.
Most regulators release air directly into the respiratory port. A resultant venturi lowers the inhalation chamber pressure and reduces inhalation effort. However the venturi can become self-sustaining and spontaneous free-flow of air may occur if the regulator is not in place in the diver's mouth. U.S. Pat. No. 4,010,746, to Pedersen, teaches a vane extending into the respiratory port to draw water into the regulator. The inflow of water equalizes pressure across the diaphragm, thus closing the demand valve and disrupting the free-flow. Unfortunately, this approach requires that the regulator flood with harmful and corrosive sea water.
Compressed air cools as it exits the demand valve and moisture in the diver's exhalation condenses and can freeze on the demand valve if the regulator is used in cold water. This can cause the demand valve to remain open and result in an irritating and potentially dangerous uncontrolled free-flow. U.S. Pat. No. 4,356,820, to Trinkwalder, discloses a metallic vane to capture heat from the diver's exhalation and conduct it to the demand valve, thus preventing regulator free-flow due to icing.
Regulators are frequently shared by many divers, especially in rental operations and diver training programs. Pathogenic entities from one diver can be transmitted to the next. Some bacteria, such as tuberculosis, have become resistant to antibiotics. Hepatitis is difficult to kill and can survive on dry surfaces for great periods of time. And lethal new viruses, such as HIV, Marburg, and Ebola are emerging with an alarming frequency. Regulators are rinsed with fresh water after use, but this has little pathogen inactivating value. There is growing concern over this problem and some instructional agencies have even discontinued so-called buddy breathing exercises to minimize the risks associated with sharing regulators between students.
U.S. Pat. No. 5,570,702, to Forman, shows a disposable cover to place over the mouthpiece before each use and U.S. Pat. No. 5,755,222, to Pansard, discloses a fastener to facilitate mouthpiece replacement. Both teach against the common use of mouthpieces, thus averting the transmission of communicable diseases. However, both fail to recognize that pathogenic entities are carried past the mouthpiece and into the regulator with exhaled air and saliva. Once there, they can be transmitted to the next user.
None of these inventions, or others of the like, taken separately or collectively, resolve all problems resulting from the open nature of the modern regulator. Some do not even resolve the issues they were intended to. And so, even after fifty years, there still remains a need to improve the operation of diving regulators.